Aluminum Tolerance of Wheat Cultivars Related to Region of Origin¹

Abstract

Abstract On certain acid soils of Ohio, certain Indiana‐developed wheat ( Triticum aestivum L.) cultivars have performed poorly relative to Ohio cultivars. Preliminary observations suggested the possibility that Ohio cultivars, in general, have been indirectly selected for greater tolerance to Al toxicity than those from Indiana. This hypothesis was tested by growing 27 established cultivars and 19 experimental lines in greenhouse pots of acid (initial pH 4.2 to 4.4), Al‐toxic, Bladen clay loam treated with 0 or 3,000 ppm CaCO 3 On the basis of relative yield (no lime/lime %), the maximum range of tolerance to the unlimed soil was 8‐ fold for tops and 12‐fold for roots. Cultivars showing greatest tolerance included ‘Thorne’ and ‘Seneca’ (Ohio origin); among those showing least tolerance were ‘Arthur’ and ‘Redcoat’ (Indiana origin). Differential Al tolerance among these four cultivars was also confirmed in nutrient solutions. With 4 ppm P in solution, the relative root yields (2 ppm Al/no Al %) were 42.7, 57.0, 13.3, and 5.4% for Thorne, Seneca, Arthur, and Redcoat, respectively. In this experiment the top yields of the four cultivars did not differ appreciably in response to Al. However, with a lower P level in solution (2 ppm) the cultivars differed in both top and root growth under Al stress. Relative root yields (3 ppm Al/no Al %) for Thorne and Redcoat were 48.4 and 14.9%, respectively; corresponding relative top yields were 45.1 and 34.5%. Under Al stress the Al‐sensitive Redcoat and Arthur maintained the pH of nutrient solutions at lower levels than the more tolerant Thorne and Seneca. Greater Al sensitivity in Arthur and Redcoat cultivars was not consistently associated with higher concentrations of Al or with lower concentrations of Ca or P within plant tops or roots. We concluded that the older Ohio wheat cultivars have been selected, unknowingly, for greater Al tolerance than those in Indiana, and that this trait has been maintained in many of the newer Ohio lines which have been developed on more heavily limed sites, where Al toxicity is not a factor. The results suggest the possibility of breeding wheat cultivars for better adaptation to acid surface or subsurface soils in which the complete neutralization of acidity is mechanically difficult, economically unfeasible, or otherwise undesirable.